Expanded Phylogenetic Representation of Genera Opercularia and Epistylis Sheds Light on the Evolution and Higher‐Level Taxonomy of Peritrich Ciliates (Ciliophora: Peritrichia)

ABSTRACT. We have generated 18S rRNA sequences for peritrichs collected in Brazil, including four Opercularia species, two different populations of Epistylis plicatilis (one epibiont and another free‐living), and one additional Epistylis species. Our Opercularia species clustered with the previously available Opercularia microdiscum, corroborating the monophyly of this genus. The Epistylis sampled here clustered with previously sequenced species of this genus. The two populations of E. plicatilis collected in Brazil clustered closely together despite their different ecological contexts, whereas both were very divergent from the sample assigned to the same species previously sampled in China. If affirmed by additional morphological corroboration of species assignment, this observation would indicate that samples from different continents morphologically allocated in the same species may in fact belong to distant evolutionary lineages. More broadly, our results support the recognition of two major clades within Peritrichia. Given the robustness of their support, we suggest that these two clades should be formally recognized as orders, and propose the names Vorticellida and Operculariida to designate them. Furthermore, Epistylis species occurred in both orders, tending to occupy basal positions. This suggests that characters used to define this genus may be plesiomorphic for Peritrichia, so that Epistylis may in fact represent an assemblage of basal species retaining ancestral features.     

Lineage sorting in multihost parasites: Eidmanniella albescens and Fregatiella aurifasciata on seabirds from the Galapagos Islands

Parasites comprise a significant percentage of the biodiversity of the planet and are useful systems to test evolutionary and ecological hypotheses. In this study, we analyze the effect of host species identity and the immediate local species assemblage within mixed species colonies of nesting seabirds on patterns of genetic clustering within two species of multihost ectoparasitic lice. We use three genetic markers (one mitochondrial, COI, and two nuclear, EF1‐α and wingless) and maximum likelihood phylogenetic trees to test whether (1) parasites show lineage sorting based on their host species; and (2) switching of lineages to the alternate host species depends on the immediate local species assemblage of individual hosts within a colony. Specifically, we examine the genetic structure of two louse species: Eidmanniella albescens, infecting both Nazca (Sula granti) and blue‐footed boobies (Sula nebouxii), and Fregatiella aurifasciata, infecting both great (Fregata minor) and magnificent frigatebirds (Fregata magnificens). We found that host species identity was the only factor explaining the patterns of genetic structure in both parasites. In both cases, there is evident genetic differentiation depending on the host species. Thus, a revision of the taxonomy of these louse species is needed. One possible explanation of this pattern is extremely low louse migration rates between host species, perhaps influenced by fine‐scale spatial separation of host species within mixed colonies, and low parasite infrapopulation numbers.     

On the reliability of the growth rings in two species of the family Characidae in the Sudan

The scales, opercula and vertebrae from 69 Hydrocyon forskali and 63 Alestes dentex were investigated for their reliability as aging structures. In both species the scales were unreliable due to their regenerative property, in spite of the clarity of their growth rings.Back-calculated lengths from the first growth ring laid on opercula and vertebrae resulted in values that coincided with the annual growth of the two species. In H. forskali, the mean back-calculated length from the two bones were 16.2 ± 5.9 and 16.8 ± 4.4 respectively, and for A. dentex, 11.1 ± 1.7 and 12.8 ± 1.8, respectively.Predictive equations for bone radius from fish length were written for both species. In this study, reliability was maximal between the observed and back-calculated lengths for both species (r > 0.95).     

Conocephalum salebrosum Szweykowski,Buczkowska & Odrzykoski (Marchantiopsida): modelling the occurrence of a hygrophytic species new to the bryoflora of Portugal,Madeira and Azores

Abstract

Conocephalum salebrosum Szweykowski, Buczkowska & Odrzykoski, a hygrophytic species, is newly reported for several localities in continental Portugal as well as in Madeira and Azores Islands. Information from studied specimens, and a map showing the actual distribution of this species and its closely related species, C. conicum (L.) Dumort., are provided as the basis for a discussion on the chorology and ecological ranges of both species. Additionally, a model of the potential distribution for both species in continental territory is developed through the Maximum Entropy Modelling technique, followed by an explanation of an hypothesis on the preferences of each species of Conocephalum known in this territory.     

The significance of carnivory for the fitness of Drosera in its natural habitat

Summary A field study of two carnivorous plant species, Drosera intermedia and D. rotundifolia, was carried out in a small silting-up bog in Southern Bavaria (FR Germany). Various parameters of undisturbed individuals of both species were measured for a period of two years and subjected to a partial correlation analysis. The importance of prey as a limiting factor for various fitness parameters was confirmed for both species. Other factors may occasionally also be limiting, e.g. assimilation area and water supply. Benefits obtained from the prey are partly transferred to the next year via the winter bud. The importance of the relative demonstrated: Plants of D. rotundifolia showed higher fitness values in higher positions, those of D. intermedia in lower positions. Growth characteristics of both species tended to influence the height of their own position in a corresponding direction: D. intermedia downwards and D. rotundifolia upwards. In both species negative effects of intraspecific neighbourhood were evident, whereas interspecific effects were not detectable. Plants of D. intermedia tend to influence their neighbourhood situation by changing their position by rhizome-like stem growth. In D. intermedia the decision to reproduce by seeds or axillary buds seems to be made at least partially already in the year before. D. rotundifolia was only observed reproducing by seeds. In spite of different catching characteristics (plant shape, plant size, microhabitats, prey spectra), the general catching success, measured as prey biomass per plant biomass, was equal in both species of sundew. This agrees with earlier findings that in this bog both species have the same biomass per ground area.     

A comparison of the population ecology of Asellus aquaticus (L.) and Asellus meridianus rac. in the reed beds of the Tjeukemeer

The population ecology of Asellus aquaticus and Asellus meridianus was studied in a Tjeukemeer reed bed from March to October. The densities of the two species are similar at the beginning and end of the reproductive season, although A. meridianus is up to 3 times more abundant in between. In both species egg production is positively correlated to body length and summer brood sizes are smaller than in the spring. A. meridianus begins to reproduce at smaller sizes than A. aquaticus and is also more fecund for overlapping size classes. Over the season as a whole both species have the same reproductive output. The life cycles of the two species are very similar with three main periods of reproduction and the populations being replaced twice during the year. Despite the differences between the species no factors are found which gives one species an obvious competitive advantage against the other.Henry and Magniez (1970) have proposed the name Proasellus meridianus for this species.     

Species of Dickinsonia Sprigg from the Ediacaran of South Australia

An iconic member of the Ediacara Biota, Dickinsonia Sprigg is one of few such taxa with multiple species. Here we use Gaussian finite mixture models to assess the validity of species distinctions for this genus. Our results indicate that the five described species of Dickinsonia from the Ediacara Member, South Australia are better classified as two based on multiple approaches. Two different methods for dimension reduction both provide strong support for two groups, with overlapping but distinct mixture models. The variable selection method produces the most biologically realistic clusters, indicating that the two species can be primarily differentiated based on the greater relative size of the anterior most unit of Dickinsonia costata Sprigg compared with Dickinsonia tenuis Glaessner & Wade. Despite differences in aspect ratio and number of modules, both species regulated growth to maintain overall shape. The greater likelihood of preservation of a midline and an irregular outer margin in D. tenuis highlights differential structural integrity and flexibility. Co-occurrence in the Ediacara Member indicates that both species occupied the same environments and temporal distribution. Smaller maximum and average size for D. costata, combined with higher abundance, may suggest a comparatively shorter lifespan and increased rates of reproduction.     

Colonization of the Tibetan Plateau by the homoploid hybrid pine Pinus densata

Pinus densata is an intriguingly successful homoploid hybrid species that occupies vast areas of the southeastern Tibetan Plateau in which neither of its parental species are present, but the colonization processes involved are poorly understood. To shed light on how this species colonized and became established on the plateau, we surveyed paternally inherited chloroplast (cp) and maternally inherited mitochondrial (mt) DNA variation within and among 54 populations of P. densata and its putative parental species throughout their respective ranges. Strong spatial genetic structure of both cp and mtDNA were detected in P. densata populations. Mitotypes specific to P. densata were likely generated by complex recombination events. A putative ancestral hybrid zone in the northeastern periphery of P. densata was identified, and we propose that the species then colonized the plateau by migrating westwards. Along the colonization route, consecutive bottlenecks and surfing of rare alleles caused a significant reduction in genetic diversity and strong population differentiation. The direction and intensity of introgression from parental species varied among geographic regions. In western parts of its range, the species seems to have been isolated from seed and pollen flow from its parent species for a long time. The observed spatial distribution of genetic diversity in P. densata also appears to reflect the persistence of this species on the plateau during the last glaciation. Our results indicate that both ancient and contemporary population dynamics have contributed to the spatial distribution of genetic diversity in P. densata, which accordingly reflects its evolutionary history.     

Body mass,measurements and moult of the White-necked Picathartes,Picathartes gymnocephalus,in Sierra Leone

We surveyed the bird species richness and abundance at 12 sites in gardens and four sites in natural woodlands at Prince Albert, Western Cape, South Africa, over a two-month period, from 14 September to 15 November 1999. Bird numbers were estimated using point counts. Of a total of 75 bird species recorded, 34 species occurred in both garden and natural sites, 23 species only in gardens and 18 species only in natural woodland. The sites in natural habitats had the greatest similarity between species. The commonest species nesting in gardens during this study was the Cape Sparrow (Passer melanurus), followed by the Laughing Dove (Streptopelia senegalensis), and Greater Striped Swallow (Hirundo cucullata). Bar-throated Apalis (Apalis thoracica), Namaqua Warbler (Phragmacia substriata), Fiscal Flycatcher (Sigelus silens) and Common Fiscal (Lanius collaris) nests were only observed at the natural sites. Southern Double-collared Sunbird (Cinnyris chalybea) and Cape White-eye (Zosterops capensis) nested in both natural and garden sites. Tree hole-nesting species were rare in both gardens and natural woodland, but this reflects the paucity of suitable sites rather than the rarity of the species per se. With the exception of two sites that lacked nectarivores, all foraging guilds were represented at all sites. There was a marked difference in numbers of insectivorous, granivorous and omnivorous species between the natural woodland sites and the garden sites. The gardens showed a gradient in species richness from the gardens with structurally simple vegetation (bare ground) through to the richest species assemblages in the structurally most diverse habitats (trees). However, this gradient was less clear than expected. Structurally fairly simple vegetation (but abundant 'flowers') had species numbers almost as high as the woodland sites, and higher than the garden tree sites.     

Mycophagy in small mammals: A comparison of the occurrence and diversity of hypogeal fungi in the diet of the long-nosed potoroo Potorous tridactylus and the bush rat Rattus fuscipes from southwestern Victoria,Australia

Abstract Three broad dietary categories—fungus, plant and arthropod—were identified from faecal samples of two species of small terrestrial mammal in forest vegetation in southwestern Victoria. Fungal material formed the major component of the diet of the long-nosed potoroo Potorous tridactylus throughout the year and of the bush rat Rattus fuscipes during autumn and winter. Fungal material was most abundant for both species during autumn and winter and significantly less common in spring and summer. These results confirm previous studies which found P. tridactylus to be highly mycophagous throughout the year and R. fuscipes to be strongly mycophagous seasonally. Particular consideration was given to the composition of fungi in the diet. Fungal spores in faecal material were assigned to spore classes, which represent one or more fungal species that have similar spore morphology. Twenty-four fungal spore classes were recorded, but for both animal species most of the fungi consumed were from seven major spore classes. The proportions of major spore classes in the diet of both animals were generally similar, even though the composition of spore classes differed markedly across seasons. Minor differences between species in the fungi consumed may be related to differences in selectivity, foraging, or microhabitat use. If fungal resources are limiting, competition for such resources may be important in this and other small mammal communities. The amount and diversity of hypogeal fungi consumed by the two animal species makes them both important spore dispersal agents in forest ecosystems. The capacity of R. fuscipes and other seasonally mycophagous mammals in this role may be more important than previously recognized, especially in habitats where species of the Potoroidae are absent.     

Biological criteria for the exploitation of the commercially important species of Gelidium in Spain

Exploitation of the commercially-important species of Gelidium in Spain (G. sesquipedale and G. latifolium) and development of the industry occurred after World War II, as a consequence of their use as resources for the extraction of agar. This resulted in the implementation of several harvesting methods, the most important of which is the gathering of cast seaweeds, both from the shore and the sea. From the very beginning, direct exploitation of these species (i.e. plucking) was controversial because of possible adverse ecological effects. Consequently, several biological and ecological studies of both species of Gelidium were begun. This included such aspects as growth, biomass production, productivity, reproduction, regeneration capacity and agar yield. Recently, the growing interest in using and conserving this resource has led to increased knowledge of the biology and ecology of these species. In this paper, we provide an overview of the research carried out by different Spanish groups and suggest guidelines for rational management of these resources.     

Calibrating the molecular clock beyond cytochrome b: assessing the evolutionary rate of COI in birds

Estimating the age of species or their component lineages based on sequence data is crucial for many studies in avian evolutionary biology. Although calibrations of the molecular clock in birds have been performed almost exclusively using cytochrome b (cyt b), they are commonly extrapolated to other mitochondrial genes. The existence of a large, standardized cytochrome c oxidase subunit I (COI) library generated as a result of the DNA barcoding initiative provides the opportunity to obtain a calibration for this mitochondrial gene in birds. In this study we compare the evolutionary rate of COI relative to cyt b across ten different avian orders. We obtained divergence estimates for both genes from nearly 300 phylogenetically independent pairs of species through the analysis of almost 5000 public sequences. For each pair of species we calculated the difference in divergence between COI and cyt b. Our results indicate that COI evolves on average 14% slower than cyt b, but also reveal considerable variation both among and within avian orders, precluding the use of this value as a standard adjustment for the COI molecular clock for birds. Our findings suggest that this variation is partially explained by a clear negative relationship between the difference in divergence in these genes and the age of species. Distances for cyt b are higher than those for COI for closely related species, but the values become similar as the divergence between the species increases. This appears to be the result of a stronger pattern of negative time‐dependency in the rate of cyt b than in that of COI, a difference that could be related to lower functional constraints on a small number of sites in cyt b that allow it to initially accumulate mutations more rapidly than COI.     

Acoustic Component and Social Context of the Wing Display of the Walnut Fly Rhagoletis juglandis

Courtship signaling via wing vibration, accompanied by sound production, has been reported in several species of tephritids. In this large family of flies, sound communication as well as complex courtship displays appears to be restricted to species with lekking mating systems (i.e., Mediterranean fruit fly, Anastrepha and Dacus species). In contrast, in tephritid species with resource-defense mating systems, such as species in the genus Rhagoletis, little or no courtship behavior, acoustical or otherwise, has been described. Wing displays in Rhagoletis species have been considered to play a visual role. This study describes a distinctive wing display performed by males of the walnut fly, Rhagoletis juglandis. Laboratory experiments and field observations demonstrate that the male wing display plays a role in courtship. We used sound and vibration detectors to record the signals produced by this wing display. Using a combination of techniques, we were able to record both the very low-frequency vibration and its accompanying airborne infrasound (12–22 Hz) produced by the males.     

Genetic distinctness of parthenogenetic forms of European Polydrusus weevils of the subgenus Scythodrusus

Abstract Among eight species of Polydrusus weevils which belong to subgenus Scythodrusus, at least two possess parthenogenetic forms: P. (S.) inustus and P. (S.) pilifer. Both of these species consist of dioecious populations in the Caspian area and of parthenogenetic populations in Eastern Europe (P. (S.) inustus), the Caucasus region (both species) and Middle Asia (P. (S.) pilifer). The origin of parthenogenesis in this subgenus is unresolved; however some data suggest that the parthenogenetic forms are of hybrid ancestry. The genetic distinctness of parthenogenetic Scythodrusus was assessed on the basis of COII, ITS2, EF1‐α and Wolbachiawsp, 16S ribosomal DNA, ftsZ and hcpA sequence comparisons. Both taxa turned out to be monophyletic for all markers, which is an evidence against hybridization of their dioecious ancestors. On the other hand, a high frequency of heterozygous P. (S.) inustus females suggests an origin resulting from hybridization between genetically distinct dioecious representatives of this species. Very similar strains of Wolbachia supergroup A were found in both species, indicating that they have been either inherited from a common ancestor or were transmitted between parthenogenetic Scythodrusus weevils and probably spread randomly across their ranges.     

Review of the distribution of Mesoplodon species (order Cetacea, family Ziphiidae) in the North Atlantic

Four species of beaked whales of the genus Mesoplodon regularly occur in the North Atlantic. These are Sowerby's Beaked Whale Mesoplodon bidens, Blainville's Beaked Whale Mesoplodon densirostris, Gervais Beaked Whale Mesoplodon europaeus and True's Beaked Whale Mesoplodon mirus. These four species differ in their distribution within this area. M. bidens is the most northerly recorded species followed by M. mirus. M. densirostris and M. europaeus both generally occur further south and their distributions cross the equator. The distribution of Mesoplodon species may relate to variations in water temperature.     

Divergent sympatric lineages of the Atlantic and Indian Ocean crinoid Tropiometra carinata

The shallow water comatulid crinoid Tropiometra carinata is native to both the Atlantic and Indian Oceans, a distribution anomalous among shallow water crinoids and many other broadcast spawning species. Given this species' short pelagic larval duration, the findings of previous work that suggest that the Benguela upwelling is a significant barrier to gene flow in broadcast spawning species, and T. carinata's unexpected geographic distribution, we predicted that the crinoids presently recognized as T. carinata consisted of a species complex. To test this prediction, we sequenced a portion of the mitochondrial cytochrome oxidase 1 gene from 30 individuals of T. carinata collected from Brazil, the Mozambique Channel, Madagascar, and Reunion Island. We found that nucleotide divergence ranged 0.02–3.10% among haplotypes. Moreover, while a Bayesian phylogenetic tree indicated that there were two substantially divergent genetic lineages, there was no evidence to support that T. carinata is comprised of a species complex due to isolation‐by‐distance. Surprisingly, both lineages were found in sympatry in both the Atlantic and Indian Oceans. Likewise, a 95% parsimony haplotype network revealed that identical haplotypes are found in both oceans, suggesting that a species complex may indeed exist, just not one caused by geographic isolation. We discuss possible explanations for this unexpected genetic structure, such as natural dispersal or human‐mediated movement, and how the genetic structure found here is relevant to other marine organisms and to cryptic speciation.     

The evolution of reproductive isolation in the Drosophila yakuba complex of species

In the Drosophila melanogaster subgroup, the yakuba species complex, D. yakuba, D. santomea and D. teissieri have identical mitochondrial genomes in spite of nuclear differentiation. The first two species can be readily hybridized in the laboratory and produce fertile females and sterile males. They also form hybrids in natural conditions. Nonetheless, the third species, D. teissieri, was thought to be unable to produce hybrids with either D. yakuba or D. santomea. This in turn posed the conundrum of why the three species shared a single mitochondrial genome. In this report, we show that D. teissieri can indeed hybridize with both D. yakuba and D. santomea. The resulting female hybrids from both crosses are fertile, whereas the hybrid males are sterile. We also characterize six isolating mechanisms that might be involved in keeping the three species apart. Our results open the possibility of studying the history of introgression in the yakuba species complex and dissecting the genetic basis of interspecific differences between these three species by genetic mapping.     

Biotic constraints on the invasion of diffuse knapweed (Centaurea diffusa) in North American grasslands

Knapweeds (Centaurea spp.) are among the most invasive of non-indigenous plant species that have colonized western North America over the last century. We conducted a 4-year experiment in a reconstructed grassland to test hypotheses related to the ability of grasslands to resist the invasion of diffuse knapweed (C. diffusa). We experimentally invaded C. diffusa and three native species into areas where we manipulated soil nitrogen (N) and phosphorus (P) availability and removed extant grasses to reduce competition. We evaluated the growth response of these species to these resources and competitive manipulations. Of the native species that were experimentally added, only one species, Ratibida pinnata (prairie coneflower), established in any numbers. Establishment values in intact vegetation were low for both species, but establishment by C. diffusa (0.02%) clearly outperformed that of R. pinnata (0.001%). Under reduced grass competition, establishment was enhanced, but the values for C. diffusa (0.68%) were not statistically different from those of R. pinnata (0.57%). Neither species performed better under higher soil nutrients in the presence of competing grasses. In plots with both species, biomass of the two planted species was positively correlated, but the biomass of both species was negatively correlated with non-added weedy species. Subsequent harvests of C. diffusa indicated that establishment was enhanced in treatments with higher soil nutrients but that the biomass of these plants could only be enhanced when plant competition was also reduced. These results indicate that C. diffusa can establish in intact grasslands at rates higher than natives, but opportunism rather than competitive ability best describes the invasiveness of C. diffusa. Thus, the mechanisms contributing to the establishment of this knapweed species are different from factors identified as contributing to the dominance of this invader.     

Bewsiella Domrow (Acarina: Mesostigmata): a revision and the description of new species

The genus Bewsiella is considered to comprise a considerable number of species, despite having been regarded as monotypic. The structure of the male spermadactyl is proposed as a key character for separating congeneric species. This character seems likely to bear phylogenetic information on both the mites themselves and their hosts. Since the male of Bewsiella fledermaus Domrow, the type-species, has not been found, it is impossible to define the morphology of this species based on both sexes. Consequently, all mites that share many characters with the female of B. fledermaus are placed in a B. fledermaus species group. B. aelleni (Till) is considered as a valid species and both sexes and the protonymph are redescribed and illustrated. B. nycteris n. sp., B. emballonuris n. sp., B. cloeotis n. sp., B. haradai n. sp. and B. coelopos n. sp. are described and illustrated. The genus Bewsiella was originally allocated to the family Laelapidae and later transferred to the family Macronyssidae. Recently, the genus was returned to the Laelapidae, and some evidence supporting this action was obtained during the present study, but further studies are required for confirmation.